The present invention relates to an alignment apparatus, a device apparatus, a measurement apparatus, and a processing apparatus for an exposure apparatus used in the lithography steps in the process of manufacturing a semiconductor or the like, and a weight compensation apparatus and the stage apparatus used in the above apparatuses.
An apparatus called a stepper is conventionally known as an exposure apparatus used in the manufacture of a semiconductor device or the like. The stepper two-dimensionally moves a substrate step by step with respect to a projection optical system for projecting the pattern of a master such as a reticle or mask onto a substrate such as a wafer, and exposing one substrate to the pattern of the master by a plurality of number of times.
As the integration degree of a semiconductor device or the like increases, higher precision is demanded for a stage apparatus for moving a substrate such as a wafer step by step and aligning it with respect to the projection optical system of the stepper.
An X-ray exposure apparatus using an exposure beam such as a soft X-ray (charged-particle storage ring radiation) which has recently been developed adopts a vertical stage which vertically holds a substrate such as a wafer and two-dimensionally moves it step by step within a vertical or approximate reference plane. This vertical stage requires, e.g., a counter mass mechanism for compensating for the weight of the stage in order to move the stage in the gravitational direction.
FIG. 10 is a schematic view showing the pulley weight compensation mechanism of a vertical stage according to the prior art. This mechanism is an X-Y stage having a Y stage 1020 which freely reciprocates along the Y-axis (vertical direction) along a surface plate 1010 standing on a base plate 1010a, an X stage 1030 which freely reciprocates along the X-axis on the Y stage 1020, an actuator (not shown) for moving the Y stage 1020 along the Y-axis, and a linear motor (not shown) for moving the X stage 1030 along the X-axis.
The surface plate 1010 has a guide surface which supports the lower surface of the Y stage 1020 in a non-contact manner via an air pad or the like. A Y guide (yaw guide; not shown) for guiding the Y stage 1020 along the Y-axis is attached to one end of the surface plate 1010. The Y guide and Y stage 1020 are also held in a non-contact manner via an air pad or the like.
A weight compensation mechanism 1060 for canceling the weights of the Y stage 1020, the X stage 1030, and a wafer or the like (not shown) held by them comprises a belt 1062 which suspends the Y stage 1020 at one end and a counter mass 1061 at the other end, and a pulley 1063 which supports and winds the belt 1062 around it. The weight of the counter mass 1061 is set to be balanced with the weight of the stage movable portion including the Y stage 1020, the X stage 1030, and a wafer or the like held by them.
There is proposed a method using a full radial hydrostatic bearing 1190 as a bearing which supports a pulley 1163, as shown in FIG. 11. FIG. 11 is a view showing a full radial hydrostatic bearing used at a pulley bearing portion according to another prior art arrangement. In FIG. 11, a reference numeral 1110 denotes a surface plate; 1190a, a bearing base; and 1190b, a hydrostatic bearing.
Since the prior art arrangements use a full radial bearing, if the shaft is not eccentric, the pressures in upper and lower bearing gaps cancel each other, and no load-carrying capacity is applied. That is, because equal power is applied to the shaft from its perimeter, the combination power to the shaft is counterbalanced when there is no eccentricity of the shaft. The full radial bearing requires a relative eccentricity between the shaft and the bearing in order to support the load. In some cases, the eccentric amount may be restricted, and the load-carrying capacity of the hydrostatic bearing may become insufficient. That is, a radial bearing of the perimeter type is suitable for supporting the rotation of the shaft, but it is not suitable for compensating for the weight of the shaft.
The present invention has been made to overcome the conventional drawbacks, and has as its object to increase the load-carrying capacity of a hydrostatic bearing for supporting a pulley shaft in a weight compensation apparatus using a pulley.
It is another object of the present invention to provide a stage apparatus having the weight compensation apparatus.
The present invention provides a weight compensation apparatus for compensating for a weight of a stage movable along a vertical reference plane, comprising: a pulley; a belt which is wound around and supported by the pulley, and has the stage at one end and a counter mass corresponding to the stage at the other end; and a hydrostatic bearing which has an arcuated bearing portion, and supports a pulley shaft by flowing a fluid into a bearing gap between the bearing portion and the pulley shaft of the pulley.
The present invention provides a stage apparatus comprising: a stage which moves in at least a vertical direction along a vertical reference plane; a pulley disposed above the stage; a belt which is wound around and supported by said pulley, and has the stage at one end and a counter mass corresponding to the stage at the other end; and a hydrostatic bearing which has an arcuated bearing portion, and supports a pulley shaft by flowing a fluid into a bearing gap between the bearing portion and the pulley shaft of the pulley.
The present invention provides an exposure apparatus using the stage.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.